Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/02—Ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0846—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms
  • C08L23/0869—Acids or derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0846—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms
  • C08L23/0853—Vinylacetate
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/52—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
  • C09K8/524—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning organic depositions, e.g. paraffins or asphaltenes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/58—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
  • C09K8/588—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids characterised by the use of specific polymers
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/18—Organic compounds containing oxygen
  • C10L1/192—Macromolecular compounds
  • C10L1/195—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • C10L1/197—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds derived from monomers containing a carbon-to-carbon unsaturated bond and an acyloxy group of a saturated carboxylic or carbonic acid
  • C10L1/1973—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds derived from monomers containing a carbon-to-carbon unsaturated bond and an acyloxy group of a saturated carboxylic or carbonic acid mono-carboxylic
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L10/00—Use of additives to fuels or fires for particular purposes
  • C10L10/14—Use of additives to fuels or fires for particular purposes for improving low temperature properties
  • C10L10/16—Pour-point depressants
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B37/00—Methods or apparatus for cleaning boreholes or wells
  • E21B37/06—Methods or apparatus for cleaning boreholes or wells using chemical means for preventing or limiting, e.g. eliminating, the deposition of paraffins or like substances
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
  • F17D1/00—Pipe-line systems
  • F17D1/08—Pipe-line systems for liquids or viscous products
  • F17D1/16—Facilitating the conveyance of liquids or effecting the conveyance of viscous products by modification of their viscosity
  • F17D1/17—Facilitating the conveyance of liquids or effecting the conveyance of viscous products by modification of their viscosity by mixing with another liquid, i.e. diluting
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2201/00—Properties
  • C08L2201/56—Non-aqueous solutions or dispersions
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2270/00—Specifically adapted fuels
  • C10L2270/10—Specifically adapted fuels for transport, e.g. in pipelines as a gas hydrate slurry

Definitions

• the present invention relates to copolymers comprising ethylene, vinyl esters, in particular vinyl acetate and esters of (meth)acrylic acid, selected from esters comprising branched alkyl, cyclic alkyl or optionally alkyl substituted aryl moieties and having a weight average molecular weight of 35,000 g/mol to 150,000 g/mol, formulations of such copolymers in organic solvents and their use as pour point depressant, wax inhibitor and flow enhancer for crude oils.
• Underground mineral oil formations typically have relatively high temperatures. After the production of the crude oil to the surface, the crude oil produced therefore cools down to a greater or lesser degree according to the production temperature and the storage or transport conditions.
• crude oils have different proportions of waxes, which consist essentially of long-chain n-paraffins.
• the proportion of such paraffins may typically be 1 to 30% by weight of the crude oil.
• the paraffins can crystallize, typically in the form of platelets.
• the precipitated paraffins considerably impair the flowability of the oil.
• the platelet-shaped n-paraffin crystals can form a kind of house-of-cards structure which encloses the crude oil, such that the crude oil ceases to flow, even though the predominant portion is still liquid.
• the lowest temperature at which a sample of an oil still just flows in the course of cooling is referred to as the "pour point".
• standardized test methods are used for the measurement of the pour point.
• Precipitated paraffins can block filters, pumps, pipelines and other installations or be deposited in tanks, thus entailing a high level of cleaning.
• the deposit temperature of oil deposits is generally above room temperature, for example 40°C to 100°C. Crude oil is produced from such deposits while still warm, and it naturally cools more or less quickly to room temperature in the course of or after production, or else to lower temperatures under corresponding climatic conditions. Crude oils may have pour points above room temperature, so such that crude oils of this kind may solidify in the course of or after production.
• Suitable additives firstly prevent the formation of said house-of-cards-like structures and thus lower the temperature at which the crude oil solidifies.
• additives can promote the formation of fine, well-crystallized, non-agglomerating paraffin crystals, such that undisrupted oil transport is ensured.
• Such additives are referred to as pour point depressants or flow improvers.
• DE 20 47 448 A discloses additives for lowering viscosity in paraffin-based crude oils.
• the additives are mixtures of polyvinyl ethers and ethylene-vinyl acetate copolymers.
• DE 19 02 925 A discloses copolymers of 40 % to 89 % by wt. of ethylene, 10 % to 40 % by wt. of vinyl esters of monocarboxylic acids having 2 to 4 carbon atoms, and 1 to 30 % by wt. of C 10 to C 22 alkyl esters of (meth)acrylic acid or vinyl esters of monocarboxylic acids having 10 to 22 carbon atoms having a number average molecular weight of 1,000 to 50,000, preferably 1,500 to 5,000.
• DE 190 29 25 A furthermore discloses the use of such copolymers as pour point depressants for crude oil distillates.
• US 4,156,434 discloses a terpolymer of 60 % to 89 % by wt. ethylene, 8 % to 25 % by wt. vinyl acetate, and 3 % to 15 % by wt. of a linear or branched C 12 to C 22 alkyl ester of (meth)acrylic acid having a number average molecular weight of 12,000 to 37,000. The publication does not disclose any specific C 12 to C 22 alkyl esters used. US 4,156,434 furthermore discloses the use of such terpolymers as pour point depressant for gas oils.
• EP 493 769 A1 discloses terpolymers of 40 % to 94 % by wt. of ethylene, 5 to 35 % of vinyl acetate and 1 % to 25 % of neononane carboxylic acid vinyl esters or neodecane carboxylic acid vinyl esters (i.e. branched C 9 or C 10 carboxylic acid vinyl esters) having a number average molecular weight of 500 to 5,000 g/mol and their use as additives for mineral oil distillates.
• WO 96/07718 A1 discloses an oil composition comprising a terpolymer of ethylene and two different carboxylic acid vinyl esters, one of them being the vinyl ester of a C 1 to C 5 carboxylic acid and the other one being a branched C 9 to C 15 carboxylic acid.
• WO 2005/054314 A2 discloses the use of polymers comprising 60 to 98 mol % ⁇ -olefines, preferably ethylene, 1 to 20 mol % vinyl esters, preferably vinyl acetate and 1 to 20 mol % esters of ⁇ , ⁇ -unsaturated carboxylic acids, preferably C 1 to C 20 esters as additives for fuel oils and lubricants.
• the number average molecular weight is 1,000 to 20,000, preferably 1,500 to 5,000.
• the weight average molecular weight may be 1,000 to 30,000 and M w /M n may be from 1,5 to 5.
• a copolymer of ethylene, vinyl acetate and 2-ethylhexyl acrylate is most preferred.
• WO 2009/106744 A2 discloses the use of a terpolymer comprising 78 % to 87 % by mol ethylene, 12 % to 18 % by mol vinyl acetate and 1 % to 4 % by mol acrylates, preferably 2-ethylhexyl acrylate as additive for fuel oils.
• the weight average molecular mass is 3,000 to 30,000.
• Additives for crude oil are necessarily used at the production sites of crude oil.
• Such production sites also may be offshore platforms which furthermore may be located in cold regions, e.g. arctic regions.
• Pour point depressants are generally supplied as concentrated solutions and can be formulated for use in the desired manner by the users on site.
• the products supplied should be liquid in order to avoid melting on site, and the solutions should also remain stable over a long period and not have a tendency to phase separation, such that they can be stored with great simplicity.
• copolymer (A) at least comprising ethylene, a vinyl ester, and a (meth)acrylate have been found wherein the copolymer (A) at least comprises
• a polymer composition (X) has been found at least comprising
• copolymers (A) as defined above as pour point depressants, wax inhibitors and rheology modifiers for crude oil.
• Copolymer (A) comprises as monomers at least ethylene (monomer M1), a vinyl ester (monomer M2), and a (meth)acrylate (monomer M3).
• Copolymer (A) comprises 83.5 mol % to 96.5 mol % of ethylene (monomer M1), preferably 85 mol % to 95 mol %, more preferably 86 mol % to 93 mol %, and most preferably 88 mol % to 92 mol %.
• R 1 is methyl and/or ethyl and more preferably R 1 is methyl.
• the amount of the vinyl ester(s) is 4 mol % to 10.5 mol %.
• the amount of (meth)acrylates is 0.5 mol % to 4 mol %.
• the moieties R 3a are branched alkyl moieties having 4 to 18 carbon atoms, preferably 5 to 11 carbon atoms and more preferably 8 to 10 carbon atoms.
• Examples of branched alkyl moieties R 3a comprise 2-methylpropyl-, t-butyl-, 3-methylbutyl-, 2,2'-dimethylpropyl-, 2-ethylhexyl-, 2-propylheptyl-, i-nonyl-, i-decyl-, i-undecyl-, i-dodecyl-, and i-heptadecyl-moieties, preference being given to 2-ethylhexyl and 2-propylheptyl moieties.
• R 3a is a 2-propylheptyl moiety.
• the moieties R 3b are cyclic alkyl moieties having 5 to 12 carbon atoms, preferably 6 to 10 carbon atoms. Cyclic alkyl moieties may be monocyclic or polycyclic, for example bicyclic. They may be furthermore substituted with linear and/or branched alkyl moieties. Examples of cyclic alkyl moieties R 3b comprise cyclopentyl-, cyclohexyl-, 4-methylcyclohexyl-, cycloheptyl-, bicyclo[2.2.1]heptyl-, bicyclo[2.2.2]octyl- or 2-(1,7,7-trimethyl)bicycle[2.2.1]heptyl- moieties. Preferably, R 3b is a cyclohexyl moiety.
• the moieties R 3c are optionally alkyl substituted aryl moieties having 6 to 12 carbon atoms. Examples comprise phenyl-, benzyl- or 2-phenyl ethyl- moieties.
• R 3 is selected from R 3a and R 3b , more preferably, R 3 is R 3a .
• Suitable monomers M4 are ethylenically unsaturated monomers which are copolymerizable with the monomers M1, M2, and M3. Such further monomers M4 may be used to fine tune the properties of the polymer.
• the amount of such additional monomers M4 is from 0 % to 12,5 mol %, preferably from 0 to 10 mol %, more preferably 0 to 5 mol %, and in the most preferred embodiment no additional monomers M4 are present.
• the copolymers (A) according to the invention have a weight average molecular weight M w of 35,000 g/mol to 150,000 g/mol, preferably 50,000 g/mol to 120,000 g/mol, and more preferably 60,000 g/mol to 110,000 g/mol, and for example 70,000 g/mol to 100,000 g/mol.
• the polydispersity M w /M n (M n : number average molecular weight) may be from 2 to 9, preferably from 3 to 7.
• copolymer (A) comprises 87 mol % to 93 mol % ethylene, 4 mol % to 10 mol % of vinylacetate and 1 mol % to 4 mol % of 2-propylheptyl(meth)acrylate. More preferably, copolymer (A) consists of such monomers. In a preferred embodiment such a polymer may have a weight average molecular weight M w of 60,000 g/mol to 150,000 g/mol, preferably 60,000 g/mol to 120,000 g/mol, more preferably from 65,000 g/mol to 100,000 g/mol and for example from 70,000 g/mol to 90,000 g/mol.
• the polydispersity M w /M n of such specific copolymers (A) may preferably be from 3 to 7.
• copolymer (A) comprises 87 mol % to 93 mol % ethylene, 4 mol % to 10 mol % of vinylacetate and 1 mol % to 4 mol % of 2-ethylhexyl(meth)acrylate. More preferably, copolymer (A) consists of such monomers.
• copolymer (A) comprises 87 mol % to 93 mol % ethylene, 4 mol % to 10 mol % of vinylacetate and 0.5 mol % to 4 mol % of cyclohexyl(meth)acrylate. More preferably, copolymer (A) consists of such monomers.
• the copolymers (A) according to the invention can be manufactured by radical polymerization under high-pressure conditions using suitable initiators for radical polymerization for example in stirred high-pressure autoclaves or in high-pressure tube reactors such as the methods described in WO 2005/054314 A2 . Preparation of the copolymer (A) in stirred high-pressure autoclaves is preferred. Stirred high-pressure autoclaves are known per se and a description may be found in Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, keywords: waxes, Vol. A 28, p. 146 ff., Verlag Chemie Weinheim, Basel, Cambridge, New York, Tokyo, 1996 .
• the high-pressure tube reactors which can also be employed are likewise described in said citation. Suitable pressure conditions for the polymerization are from 1000 to 3000 bar, preferably from 1500 to 2500 bar.
• the reaction temperatures are, for example, in the range from 160°C to 320°C, preferably in the range from 180 to 260°C.
• Useful initiators for free-radical polymerization are customary free-radical initiators such as organic peroxides, oxygen or azo compounds. Also suitable are mixtures of a plurality of free-radical initiators are also useful. Suitable peroxides are disclosed in US 2007/0094920 A1 , paragraphs [0068], [0069], and [0070]. Particularly useful peroxides are di-tert-butyl peroxide, tert-butyl peroxypivalate, tert-butyl peroxyisononanoate, tert-amylperoxipivalate and dibenzoyl peroxide and mixtures thereof.
• An azo compound which may be mentioned byway of example is azobisisobutyronitrile ("AIBN"). Free-radical initiators are introduced in amounts customary for polymerizations.
• the polymerization can be carried out in the presence of one or more regulators (chain transfer agents) for controlling the molecular weight of the copolymers (A).
• regulators chain transfer agents
• Suitable regulators are disclosed in US 2007/0094920 A1 , paragraphs [0056] to [0065].
• Particularly useful regulators are H 2 , propene, butene, propion aldehyde, or methylethylketone.
• the amount of the regulator used can be chosen by the skilled artisan according to his/her needs. In order to achieve the desired weight average molecular weight M w 30,000 g/mol to 150,000 g/mol it is frequently advisable to limit the amount of regulator to an amount of not more than 0.6 % by wt. relating to the total amount of all comonomers used.
• the amount of regulator is 0 to 0.2% by wt. relating to the total amount of all comonomers used. In another embodiment of the invention no regulator is used.
• the inventive copolymers (A) are prepared in such a manner that ethylene is compressed by a gas compressor to approximately 250 bar and in parallel a mixture of the comonomers M2, M3, and optionally M4 and optionally at least one regulator are also compressed separately by a pump to approximately 250 bar.
• Both, ethylene and the comonomer mixture are mixed at a pressure of approximately 250 bar and thereafter the mixture is compressed by a hypercompressor to a pressure of about 1,700 to 2,200 bar.
• the monomers and the regulator are now dissolved in supercritical ethylene.
• the mixture having a temperature from 20°C to 50°C, preferably 25°C to 35°C is passed, preferably continuously, through a stirred autoclave which is maintained at a pressure of 1,500 to 2,500 bar, for example 1,600 to 2,200 bar.
• the initiator which generally is dissolved in a suitable solvent, for example isododecane or methylethylketone is also fed - preferably continuously- into the stirred autoclave, which the comonomers are passing through thus maintaining the temperature in this stirred autoclave chosen by the skilled artisan, for example at 180°C to 260°C as indicated above.
• a suitable solvent for example isododecane or methylethylketone
• the polymer obtained after decompression of the reactor may be isolated in a customary manner.
• isolation techniques include under-water pelletizing of the melt or the melt may be dissolved directly in a suitable solvent.
• the comonomers and the regulator can be separately metered into the reactor or the reaction temperature may be varied during the process.
• a tubular reactor may be used instead of a stirred autoclave in the process described above.
• the polymer composition (X) according to the invention comprises at least one copolymer (A) as described above and at least one organic solvent (B).
• the copolymers (A) should be homogeneously dispersed, preferably dissolved in the organic solvent (B). It is of course also possible to use mixtures of different organic solvents (B).
• the organic solvents (B) may, for example, be nonpolar solvents comprising saturated aliphatic hydrocarbyl groups, preferably those having a (flashpoint ⁇ 60°C.
• solvents comprise saturated aliphatic hydrocarbons, saturated aliphatic alcohols or esters of saturated aliphatic carboxylic acids and saturated aliphatic alcohols, preferably each having a (flashpoint ⁇ 60°C.
• alcohols comprise aliphatic alcohols having at least 8 carbon atoms, such as 1-octanol, 1-decanol or 1-dodecanol.
• esters comprise esters of saturated fatty acids having at least 8 carbon atoms with saturated aliphatic alcohols, for example methyl laurate or methyl stearate.
• Technical mixtures of various aliphatic esters are commercially available.
• esters of aliphatic or cycloaliphatic dicarboxylic acids for example dialkyl esters of cyclohexane-1,2-dicarboxylic acid, such as diisononyl cyclohexane-1,2-dicarboxylate.
• organic solvents (B) comprise hydrocarbons or a hydrocarbon mixture. These may be aliphatic, cycloaliphatic and/or aromatic hydrocarbons. Preference is given to hydrocarbons or hydrocarbon mixtures having a (flashpoint ⁇ 60°C.
• the hydrocarbons may be used as a mixture of hydrocarbons with other organic solvents as outlined above. Such mixtures preferably comprise at least 50 % by weight of hydrocarbons. Most preferably, only hydrocarbons or a hydrocarbon mixture are used as organic solvent (B).
• the hydrocarbons may, for example, be saturated aliphatic solvents or solvent mixtures. These may be either paraffinic or naphthenic, i.e. saturated cyclic, hydrocarbons. Preference is given to high-boiling aliphatic hydrocarbons having a boiling point of at least 175°C and preferably a (flashpoint ⁇ 60°C. Suitable hydrocarbons having a (flashpoint ⁇ 60°C comprise, for example, n-undecane (flashpoint 60°C, boiling point 196°C) or n-dodecane (flashpoint 71 °C, boiling point 216°C).
• hydrocarbons for example mixtures of paraffinic hydrocarbons, mixtures of paraffinic and naphthenic hydrocarbons or mixtures of isoparaffins. It will be apparent to those skilled in the art that technical mixtures may still comprise small residues of aromatic or unsaturated hydrocarbons.
• the hydrocarbons may also be aromatic solvents or solvent mixtures.
• the hydrocarbons are toluene or a solvent mixture comprising toluene.
• the hydrocarbons are high-boiling aromatic hydrocarbons having a boiling point of at least 175°C and preferably a (flashpoint ⁇ 60°C. It is possible with preference to use technical mixtures of aromatic hydrocarbons.
• Technical mixtures of aromatic solvents are commercially available, for example technical mixtures of the Shellsol® A series or the Solvesso® series.
• the polymer composition (X) is prepared in the usual manner by dispersing or dissolving at least one copolymer (A) in at least one organic solvent (B). This may be done by dissolving solid copolymer (A), for instance granules of copolymer (A) in at least one organic solvent (B). In one embodiment the polymer melt obtained from polymerization may be directly dissolved in at least one organic solvent (B).
• the polymer composition (X) may of course comprise further components.
• additives which may be used in the ready-for-use formulation such as the wax inhibitors as described below.
• further components include poly(meth)acrylates, polymers comprising isobutene, ⁇ -olefines, for example copolymers of maleic acid anhydride and styrene, copolymers of maleic acid anhydride and vinylacetate, which may optionally be further reacted alcohols and amines, copolymers of maleic acid anhydride and (meth)acrylates copolymers, Copolymers of fumaric acid esters and vinyl acetate, styrene-butadiene based copolymers, or alkylphenolformaldehyde resins.
• poly(meth)acrylates polymers comprising isobutene, ⁇ -olefines
• copolymers of maleic acid anhydride and styrene copolymers of maleic acid anhydride and vinylacetate, which may optionally be further reacted alcohols and amines
• the concentration of the copolymer (A) may be 5 to 35 % by weight, preferably 10 to 30 % by weight with respect to the sum of all components of the polymer composition (X).
• copolymers (A) and/or the polymer compositions (X) may be used in various oilfield applications by adding them and/or suitable formulations thereof to crude oil.
• the copolymers (A) can be used as pour point depressants for crude oil by adding at least a copolymer (A) to the crude oil.
• pour point depressants reduce the pour point of crude oils.
• the pour point refers to the lowest temperature at which a sample of an oil, in the course of cooling, still just flows. For the measurement of the pour point, standardized test methods are used.
• a suitable formulation comprising at least a copolymer (A) and at least one solvent is added to the crude oil.
• Suitable solvents may be selected from water, polar or non-polar organic solvents.
• the copolymer(s) (A) may be dissolved or dispersed in the solvent.
• the formulations may of course comprise further components such as for instance surfactants.
• the copolymers (A) can be used as pour point depressants for crude oil by adding a suitable formulation comprising at least a copolymer (A) and an organic solvent capable of dissolving the copolymer(s) (A) to the crude oil.
• organic solvents (B) as defined above may be used.
• concentration of the copolymers (A) may also be selected by the skilled artisan an may be from 0,1 % by weight to 35 % by weight of copolymers (A) in the ready-for-use formulation.
• the formulation to be used may additionally comprise further components.
• additional wax dispersants can be added to the formulation.
• Wax dispersants stabilize paraffin crystals which have formed and prevent them from sedimenting.
• the wax dispersants used may, for example, be alkylphenols, alkylphenol-formaldehyde resins or dodecylbenzenesulfonic acid.
• the formulation comprising organic solvents comprises a composition (X).
• the polymer composition (X) may be used as such or further components as outlined above and/or further organic solvents, in particular further organic solvents (B) may be added before use.
• the formulation to be used may be formulated at or close to the site of use, i.e. at or close to the oilfield or it may be formulated in a chemical plant distant from the site of use and then provided to the site of use.
• the site of use is an offshore platform.
• a polymer composition (X) is provided to the site of use, optionally further formulated and then used. It is the advantage of the polymer composition (X) that it is a concentrate thus minimizing transport costs but remains nevertheless liquid even at low temperatures so that it can be used without the need to melt it before use.
• the inventive use is effected by adding the formulations comprising copolymer (A) and optionally comprising further components to the crude oil.
• the formulation should be added as long as the crude oil has a temperature greater or equal to its pour point.
• the formulations are typically used in such an amount that the amount of all copolymers (A) together added is 50 to 3000 ppm based on the oil.
• the amount is preferably 100 to 1500 ppm, more preferably 250 to 600 ppm and, for example, 300 to 600 ppm.
• the formulation is injected into a crude oil pipeline.
• the injection can preferably be effected at the oilfield, i.e. at the start of the crude oil pipeline, but the injection can of course also be effected at another site.
• the pipeline may be one leading onshore from an offshore platform. Explosion protection is particularly important on offshore platforms, therefore formulations based on organic solvents having a (flashpoint ⁇ 60°C accordingly simplify working quite considerably.
• the cooling of crude oil in underwater pipelines leading onshore from an offshore platform is naturally particularly rapid, especially when the pipelines are in cold water, for example having a water temperature of less than 10°C.
• the formulation is injected into a production well.
• the production well may especially be a production well leading to an offshore platform.
• the injection is preferably effected approximately at the site where oil from the formation flows into the production well. In this way, the solidification of the crude oil in the production well or an excessive increase in its viscosity can be prevented.
• the copolymers (A) are used as pour point depressant and/or paraffin inhibitor for crude oil by adding emulsions and/or dispersions of at least one copolymer (A) in a suitable solvent or solvent mixture to the crude oil.
• suitable solvents for such emulsions or dispersions include water, polar organic solvents miscible with water, including but not limited to alcohols such as methanol, ethanol, propanol, ethylene glycol, propylene glycol. Of course mixtures of two or more or more solvents may be used, for instance a mixture comprising water and an organic solvent miscible with water.
• the copolymer (A) is dispersed in a suitable solvent or solvent mixture.
• a mixture, preferably a solution of the copolymer(s) (A) in a suitable solvent is emulsified in another solvent which is not miscible with the first solvent.
• the copolymer(s) (A) may be dissolved in a non-polar organic solvent and the solution is emulsified in water and/or a polar organic solvent.
• a polymer composition (X) as described above may be emulsified in water and/or a polar organic solvent.
• said emulsions and/or dispersions of at least one copolymer (A) comprise at least one emulsifier or a mixture of emulsifiers.
• the amount of emulsifiers in a ready to use formulation is at least at least 10% by wt. with respect to the total of all components, for example 10 - 20% by weight.
• suitable emulsifiers comprise anionic or non-ionic surfactants including but not limited to ethoxylated fatty alcohols such as C 16/18 -(EO) x H with x from 5 to 50 or synthetic ethoxylated alcohols such as C 13 -(EO) y H with y from 5 to 50.
• the concentration of the copolymers (A) in the emulsions or dispersions may be from 5 to 40 % by wt. in a ready to use formulation.
• Such emulsions and/or dispersions of at least one copolymer (A) in a suitable solvent or solvent mixture may be made by melting at least the copolymer(s) (A), the emulsifier(s) and -if present- an organic solvent in a vessel until all ingredients form a homogeneous clear melt. Under stirring, water and/or a polar organic solvent is added at 90°C and stirring is continued until the formulation has been cooled down to room temperature.
• such aqueous formulations may be made is by melting at least the copolymer(s) (A), at least one emulsifier and -if present- an organic solvent in a vessel until all ingredients form a homogeneous clear melt. While stirring slowly with a low shear rate, water or a polar organic solvent is added at 90°C and stirring is continued. During the cooling process, at least one further emulsifier is added to the formulation, then it is cooled down to room temperature.
• the copolymers (A), in particular the above-detailed formulations, especially the formulations comprising polymer compositions (X) are used to prevent wax deposits on surfaces in contact with crude oil.
• the use is effected by adding at least one of the formulations detailed above to the crude oil.
• Preferred formulations have already been mentioned, and the manner of use is also analogous to the use as a pour point depressant.
• copolymers (A) according to the present invention are suitable for use as pour point depressants and also for use as wax inhibitors. Therefore it is not necessary to mix pour point depressants and wax inhibitors if both effects are desired by the skilled artisan but using one component is sufficient.
• the copolymers (A), in particular the above-detailed formulations, especially the formulations comprising polymer compositions (X) are used as rheology modifiers in order to improve the flowing properties of crude oil, e.g. of oil flowing through pipelines to lower its viscosity thereby facilitating its transport.
• the copolymers preferably a formulation of the copolymers as detailed above may be added to the crude oil.
• Part A Manufacture of the copolymers (A) and comparative copolymers
• the copolymers (A) and comparative copolymers were manufactured by radical polymerization of ethylene, vinyl acetate and the respective (meth)acrylates under high pressure in a stirred high-pressure autoclave in a continuous process.
• Ethylene (12,0 kg/h) was pressurized to 250 bar by a pre-compressor.
• Vinyl acetate, the respective (meth)acrylate used and propionaldehyde as regulator were pressurized by middle pressure pumps also until 260 bar.
• the amounts of the comonomers and propionaldeyde are provided by table 1.
• the ethylene feed and the comonomer mixture were compressed together with a hypercompressor to about 1,700 bar and the mixture was fed in the autoclave.
• tert-amylperoxypivalate dissolved in isododecane was also pressurized with another high pressure pump to 1,700 bar and also fed into the autoclave.
• the temperature in autoclave was kept constantly at around 220°C.
• the polymer is separated from the free monomers by reducing the pressure very rapidly to 1 to 20 bar.
• the resulting copolymer is collected as a melt in a heated product tank (200°C). For use it may be removed and solidified.
• Table 2 The properties of the collected copolymers are summarized in Table 2.
• Table 1 Feed of monomers and regulators into reactor polymerization, i-pentyl-, i-nonyl-, i-tridecyl-, and i-heptadecyl moieties are branched alkyl groups. No.
• Part B Test of the properties of the polymers obtained
• the number-average molecular weight M n and the weight-average molecular weight M w of each of the copolymers obtained were determined by means of gel permeation chromatography in tetrahydrofuran as the solvent using polystyrene standards. The values are compiled in table 2 and 3.
• the determination of the pour point was conducted to ASTM D97 "Standard Test Method for Pour Point of Petroleum Products.
• the pour point is the minimum temperature at which a sample of the oil used for the tests is still just free-flowing. According ASTM D97, for this purpose, a sample of the oil is cooled in steps of 3°C each and the flowability is tested after each step. For the tests, a crude oil from the "Landau” oilfield in south-west Germany (Wintershall Holding GmbH) having an API gravity of 37 and a pour point of 27°C was used.
• the graft copolymers to be tested were used to the oil in a concentration of 100 ppm, 300 ppm or 1500 ppm, in each case of polymer based on the crude oil.
• the values are compiled in table 1. Double or triple determinations were conducted on some samples. In these cases, all measurements are reported in the table. The results are summarized in table 3.
• the viscosity of the crude oil at 9°C is 2500 mPas. Furthermore, the viscosity of crude oil comprising 100 ppm of the copolymers C1 to C13 and 1 to 12 (added as 10 % solution in xylene) and the viscosity of crude oil comprising 300 ppm of copolymers C1 to C13 and 1 to 12 were measured respectively under the same conditions in order to study the influence of the copolymers on the rheological properties of the oil. The results are summarized in table 3.
• the cold finger deposition test was utilized to determine the wax inhibition properties of the terpolymers.
• the wax inhibition was determined by exposing the crude oil to a cold metal finger surface in the presence and absence of the inhibitor. The amount and type of wax deposited on the cold metal finger was used to determine waxing tendency.
• the present application relates to copolymers comprising ethylene, vinylesters and and certain (meth)acrylic acid esters which are specifically adapted for use in oilfield applications, in particular as pour point depressants, wax inhibitors, and rheology modifiers.
• copolymers comprising ethylene, vinylesters and and certain (meth)acrylic acid esters which are specifically adapted for use in oilfield applications, in particular as pour point depressants, wax inhibitors, and rheology modifiers.
• All copolymers (A) according to the invention show a wax inhibition of more than 70 %, including examples 1 to 8 which show a wax inhibition of at least 80 %. Only two of the comparative examples have a wax inhibition of 72%, resp. 73 % while all the other comparative examples show a wax inhibition of not more than 62%, in the worst case only 18%.
• Comparative example 1 also comprises 2-propylheptylacrylate but has a molecular weight M w of only 7,300 g/mol (which is well below the lower limit of 35,000 g/mol as required by our invention). Its performance as pour point depressant, wax inhibitor, and rheology modifier is the worst of all examples but also comparative examples.
• the best examples 1 and 2 have a molecular weight M w of 73,000 g/mol and 66,700 g/mol respectively.
• Example 3 which also comprises 2-propylheptylacrylate has a somewhat lower molecular weight of 48,600 g/mol. While its performance as wax inhibitior and rheology modifier still is very satisfying, its performance is no longer that good as that of examples 1 and 2.
• Comparative example 4 demonstrates the need of a sufficient amount of ethylene.
• the polymer comprises only 80 mol % ethylene (which is below the lower limit of 84 mol % ethylene required by our invention) and its performance as pour point depressant is as worse as that of comparative example 4.
• Comparative example C7 shows that linear alkyl moieties are inferior as compared to the branched of cyclic alkyl moieties of the present invention.
• the copolymer C7 comprises 1 % of n-octyl acrylate while the copolymer 7 comprises 1 % of 2-ethylhexyl acrylate. While the performance as pour point depressant is in about the same for both polymers, C7 added at a concentration of 100 ppm does nearly not reduce the oil viscosity at all, while copolymer 7 already significantly reduces it. Also at a concentration of 300 ppm the performance of copolymer is far better than that of C7.
• copolymer C7 has not a good performance as wax inhibitor (57%), while polymer 7 has an excellent performance (81 %). Similar observations may be made by comparing a linear C 12 acrylate (copolymer C8) with a branched C 13 acrylate (copolymer 11). Copolymer 11 shows a better performance as pour point depressant but also as wax inhibitor and rheology modifier.

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